The present invention relates in general to portable lathes and more particularly to a canopy removing device designed for application on nuclear components to permit replacement or maintenance of various components.
In nuclear systems and the like, removable cylindrical components are joined to other cylindrical components or are positioned in a bore which results in a need to seal the circumferential joints with protective canopies. These canopies span the joints to permit expansion and contraction while preventing any contaminated material from passing through the joint. The canopies are normally truncated conical rings having an arcuate cross-section and being welded along its two edges to the adjoining components. These canopies are normally formed of a stainless steel as are the adjoining components. When it becomes necessary to remove one of the components such as for maintenance, failure of a part or renewal of a fuel supply, the canopy must be removed without contaminating the environment and without damaging either of the two assembled components.
Previously, hand grinders have been utilized in removing canopies which has been extremely time-consuming as shown by the fact that the removal of a 53/8th inch outside diameter canopy has required twelve hours of hand grinding. Hand grinding has been exclusively employed for this purpose in nuclear reactors in the past which has required the extensive training and employment of large numbers of operators due to the fact that each worker can remain at a work station for only a very short time period to avoid over-exposure to radiation. Since the time required for the entire grinding operation is substantial, a large number of hand grinding operators is required to complete the presently employed tedious and time-consuming process. In actuality, the radiation to which these workers are exposed results in their being able to work only a few hours a month in performing tasks in this environment; moreover, the nuclear reactor environment requires the elimination of dust and lubrication, to avoid contamination which increases the exposure time hazards for the workers.
An additional problem arises from the fact that the canopies are frequently located in very constricted spaces such as small diameter bores and areas closely adjacent other components resulting in difficult access to the canopy cutting and removal of the canopy.
Attempts have been made to provide a device for removing the canopies without damaging the components to which each canopy has been welded. These devices have been complex, bulky and heavy and have required the use of skilled and expensive operators to remove even the canopies which were large and conveniently located. While this previous equipment has reduced the time required for hand grinding removal of the canopies in many instances, it has not been usable in restricted and confined spaces and has continued to require long periods of operation in radiation environments thereby requiring numerous operators to complete a given task.
It is, therefore, a primary object of the present invention to provide a new and useful canopy cutting device.
An additional object of the present invention is to provide a novel canopy cutting device which is extremely small compared to the item being removed thereby permitting its application to cutting operations in extremely confined areas.
A further object of the present invention is to provide a novel canopy cutting device which can perform efficient machining operations when used by an inexperienced operator in very confined spaces.
A further object of the present invention is to provide a novel canopy cutting device which drastically reduces the exposure of operators to radiation when the device is used to remove canopies in nuclear reactors.
Another object of the present invention is to provide a novel canopy cutting device which is extremely simple in construction and requires a minimum of maintenance over a long useful life.
A further object of the present invention is to provide a novel canopy cutting device which can be operated without any lubrication of the device or cutting tool while permitting the removal of stainless steel, inconel and other special alloys found in nuclear reactors and the like thereby eliminating a potential source of contamination and exposure time to radiation which would result from attempting to clean up the contamination.
A further object of the present invention is to provide a canopy cutting device which is capable of facing or otherwise machining the component to which the canopy is attached prior to installing another canopy.
A further object of the present invention is to provide a novel canopy cutting device which does not have excessive chattering of the tool bit and operates smoothly without part breakage or stalling.
A still further object of the present invention is to provide a machine which is simple and safe to operate with a minimum of operator skill and with all adjustments being convenient while the device is being operated in either vertical or horizontal positions.
Other objects, advantages and capabilities of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings illustrating the preferred embodiment of the invention.